Automatic Block Working is a system of train working in which movement of the trains is controlled by the automatic stop signals. These signals are operated automatically by the passage of trains ?into?, ?through? and ?out? of the automatic signalling sections. Following are the essentials of Automatic Block System.

Where trains are worked on Automatic Block System: -

(a) The line is track circuited throughout its length and divided into a series of automatic signalling sections each of which is governed by an Automatic Stop Signal.

(b) The movement of trains is controlled by stop signals, which are operated automatically by the passage of trains past the signals.

(c) No Automatic Signal assumes 'OFF' unless the line is clear not only upto the stop signal ahead, but also an adequate distance beyond it.

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